Comparative Analysis of Temperature-dependent Raman Spectra of GaN and GaN/Mg Films

Abstract

The Raman spectra of unintentionally doped gallium nitride (GaN) and Mg-doped GaN films were investigated and compared at room temperature and low temperature. The differences of E₂ and A₁(LO) mode in two samples are discussed. Stress relaation is observed in Mg-doped GaN, and it is suggested that Mg-induced misfit dislocation and electron phonon interaction are the possible origins. A peak at 247 cm^-1 is observed in both the Raman spectra of GaN and Mg-doped GaN. Temperature-dependent Raman scattering experiment of Mgdoped GaN shows the frequency and intensity changes of this peak with temperature. This peak is attributed to the defect-induced vibrational mode.